This invention relates to a new class of polyetherimides.
U.S. Pat. Nos. 3,838,097; 3,847,867; 3,847,869; 3,905,942; 3,983,093, for example, describe polyetherimides of the formula: ##STR1## where a represents a whole number in excess of 1, e.g., 10 to 10,000 or more, the group --O--A&lt; is selected from: ##STR2## R' being hydrogen, lower alkyl or lower alkoxy, preferably the polyetherimide includes the latter --O--A&lt; group where R' is hydrogen such that the polyetherimide is of the formula: ##STR3## and the divalent bonds of the --O--Z--O radical are in the 3,3'; 3,4'; 4,3' or the 4,4' position. Z is a member of the class consisting of ##STR4## and (2) divalent organic radicals of the general formula: ##STR5## where X is a member selected from the class consisting of divalent radicals of the formulas, ##STR6## where q is 0 or 1, y is a whole number from 1 to 5, and R is a divalent organic radical selected from the class consisting of (1) aromatic hydrocarbon radicals having from 6-20 carbon atoms and halogenated derivatives thereof, (2) alkylene radicals and cycloalkylene radicals having from 2-20 carbon atoms, C.sub.(2-8), alkylene terminated polydiorganosiloxane, and (3) divalent radicals included by the formula ##STR7## where Q is a member selected from the class consisting of ##STR8## where x is a whole number from 1 to 5 inclusive. Particularly preferred polyetherimides include those where --O--A&lt; and Z respectively are: ##STR9## and R is selected from: ##STR10## The polyetherimides where R is metaphenylene are most preferred.
One of the principal drawbacks of these polymers is their lack of good melt fabricability which severely limits their usefulness.
It was now unexpectedly found that the difficulty above is obviated by using oligomeric diamines EQU H.sub.2 N--R--NH.sub.2
wherein the molecular weight of R is .gtoreq.1,500.